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By G. I. Mathieu

Research and development studies were carried out at the Canada Centre for Mineral and Energy Technology to produce a synthetic forsterite sand from asbestos tailings for Les Sables Olimag Inc. The National Research Council of Canada also supported and collaborated to the project. Theoretically, the technological approach consists of a heat at over 1300°C; however, the process without additive would result in the production of an enstatite-rich product (MgSiO3) having a fusion temperature less than 1600°C. The purpose was to foster the formation of forsterite (Mg2SiO4), a more refractory compound. The fabrication of the forsterite product requires pre-agglomeration of serpentine-MgO with a binder, which is stable at high temperature, to prevent the loss of the powdered magnesium oxide as dust in the kiln off gases and to maintain the mixture homogeneous during the process. Characterization of the end products with respect to mineral composition and thermal resistance are described. The synthetic forsterite in sand form was tested with success under a bath of liquid steel maintained at 1700°C for up to two hours. The advantages of the new sand and its potential applications will be reviewed.

Jan 1, 1992

By William A. Gibson, Kenneth P. Neumann

In 1967, development of the Cyprus Thompson Creek molybdenum deposit began near Challis, ID. The first mining claims were staked on an intrusive rock out-crop. Exploration continued for 14 years. In 1978, the decision was made to develop the deposit. In Dec. 1980, approval was received for the environmental impact statement and facilities construction and waste rock removal began. By the middle of 1983, 126 Mt (139 million st) of rock had been removed and all facilities completed. Location The Thompson Creek project is located about 58 km (36 miles) southwest of Challis in Custer County, in south central Idaho. The mine and mill are situated between 2.2 and 2.6 km (7,217 and 8,530 ft) in elevation. The project is located in an isolated area. Surrounded by mountains, it is adjacent to the Sawtooth National Recreation Area. The Salmon river is 8 km (5 miles) south of the project. The project claim block is lo-

Jan 1, 1984

By P. D. Rao

The combination of high moisture and low heating value has restricted most low-rank coal (LRC) usage worldwide to mine-mouth power generation. Coals from Usibelli Coal Mine and the Beluga coal field have a heating value of approximately 8,000 Btu/lb and 28% moisture. Hydrothermal treatment (at 275 to 352'C) of lump coal from Usibelli Coal Mine and Beluga coal field enhanced the heating value of the coal, on an equilibrium moisture basis, from 8,000 Btu/lb to nearly 12,000 Btu/lb. The product coal with high heating value and 0.2 % S is an environmentally acceptable premium fuel. The Hardgrove grindability index of the coal is greatly improved, further enhancing its value. Increase in hydrothermal drying temperature promotes vesiculation of resinite. Vitrinite reflectance increased to 0.72 and vitrinite was subjected to widespread visiculation resulting in a coke like structure indicative that the material went through the fluid stage.

Jan 1, 1991

By L. Barry Phelps

The application of an open-pit Materials Handling Simulator (OPMHS) to analyze mine planning and scheduling problems in large surface mines is discussed. The mine chosen for this application employed a large stripping dragline working in tandem with a shovel-truck haulback system for removing overburden. Large bottom-dump trucks were employed behind a coal loading shovel to transport the exposed coal out of the pit. Specifically, the current operations and the recommendations for short term and long term improvements were simulated on OPMHS. The effects of changing the operating parameters of the equipment on the total system were evaluated. Several alternatives were also studied for the best use of the existing equipment if the current operating parameters could not be improved upon. The results of the application are discussed.

Jan 1, 1978

By Yun Bai, Sarah Wilson, Michael Salcher, Mark Trim

Over the last decade more than 62 miles (100 km) of civil transport tunnels were constructed in Sydney, Australia, using the sequential excavation method (SEM). The WestConnex motorway tunnels, each stage of which used over 20 roadheaders to excavate up to 40 tunnel headings, had numerous caverns up to 100 feet (30 m) wide and 82 feet (25 m) high. SEM tunnels in North America typically have far fewer active headings. This paper examines the differences in scope and risk allocation for construction phase services, including comparison of the Permit to Tunnel (PTT) process in Australia and the Required Excavation and Support process in North America.

Jun 23, 2024

By James P. Cooney

What is required for the mining industry to grow and prosper in a politically challenging world? The answer to this can be summarized as “the industry’s three priorities.” The first priority is gaining access to the world’s mineralized jurisdictions. The second is establishing a measure of security and predictability in government treatment of mining. Confidence in the stability of the fiscal and legal framework within which mining operates is necessary to encourage the investment of large amounts of capital in mine development. The third priority is sustaining the industry’s welcome during the long term in those jurisdictions worthy of investment.

Jan 1, 1996

By Gary N. Weinrich

Large surface mining projects in sparsely populated regions of the West have the potential to create disruptions in an area's social and economic character with potential effects on man that can far outweigh the physical and ecological effects on man's environment. The data and analyses involved in addressing the socioeconomic issues are additional to those traditionally associated with surface coal mining, such as those concerning land reclamation and water quality. Appropriate socioeconomic studies in conjunction with mine-planning can identify the potential problem areas in order that project measures can be taken to maximize the beneficial impacts and minimize the adverse effects of surface coal mining. The information required to conduct such socioeconomic analyses, available data sources, and the applicable analyses are described. Overall impacts of some proposed Western surface mines are summarized and potential mitigating steps discussed.

Jan 1, 1975

By D. E. Nash

Environmental compliance programs for mining companies are not only important management tools, but can deflect serious civil and criminal penalties if violations of environmental laws do occur. The paper discusses the legal foundation for such programs and their basic structure.

Jan 1, 2001

By A. J. Basu

An overview of the evolution of computerized mine planning and design has been given, emphasizing the need for a knowledge-based system for planning and design of underground coal mines. An outline for the development methodology and procedure has been provided. Problem structuring guidelines have been used to incorporate intelligence and integration to the design modules. A skeletal model for a mine planning and design expert system has been prescribed, and the development process has been documented in detail. A feasibility prototype has been developed to test the structure of the skeletal model and to ensure completeness of the design process. The feasibility prototype development and its contribution toward proto typing has been addressed in this paper. At present, prototype development is underway. The prototype is expected to be avail-able for testing and implementation in early 1991.

Jan 1, 1991

By R. W. Kobler

The pelletizing process for low grade iron ores has undergone continual changes since its inception over twenty years ago. These changes have necessitated filtration equipment changes in order to produce a product suitable for balling. With modern techniques it is now possible to produce pellets of 68% Fe from ores containing as low as 26% Fe. Low grade ores require fine grinding to liberate impurities This shift to finer grinds over the years has necessitated major changes in the filtration steps. Techniques are now available for producing suitable product from ores with Blaines as high as 3600 cm2/gram. This has been made possible by the development of high performance filters. Recent developments have reduced maintenance costs and produced higher production reliability. The paper discusses iron concentrate filtration from its beginning to present day design. It will be shown that the dewatering step prior to balling has gone through four generations of filters. Particular emphasis is placed upon hydraulic studies which have allowed today's optimum designs.

Jan 1, 1978

By Yi Luo, Jian Yang, Hua Jiang

Surface subsidence events induced by underground longwall coal mining operations can cause various disturbances to surface structures ranging from integrity and stability to functionality problems. Highway bridges, as a kind of special road construction that can only tolerate smaller movements and deformations than road pavements, are particularly susceptible to severe influence caused by subsidence-induced ground movements and deformations. However, based on accurate subsidence prediction and correct influence assessments, efficient and effective mitigation and remediation measures can be designed and implemented to ensure the continuous service of bridges, safety of the travelers and smooth mining operations. In this paper, based on the predicted final and dynamic surface movements and deformations, the techniques to assess subsidence influence on the integrity, stability and functionality of bridge structures (e.g., decks, beams, abutments, etc.) are presented. A number of mitigation measures to protect the bridge structures are recommended along with an actual application case.

By J. H. Kempton

Refinement of environmental procedures can produce significant cost savings at most mines. Grouting permeable aquifers reduces water pumping and disposal costs. Stable groundwater quality supports reduced groundwater monitoring; and for contaminated groundwater, in-situ or natural restoration should be evaluated. Waste-rock characterization can be minimized using fewer (but more representative) samples, inexpensive surrogate analyses (e.g., NAG instead of humidity cells), and appropriate tests (e.g., avoid meteoric tests on sulfide). Selective waste-rock handling should be compared to random emplacement, which is often cheaper and more stable. Finally, incorporating schedule uncertainty in modeling allows the flexibility to revise mine plans within permits.

Jan 1, 2000

By VIVEK KUMAR HIMANSHU, M. P. Roy, P. K. Singh, A. K. Mishra, RAVI SHANKAR

Blasting with the aim to reduce oversize boulders in underground has many hurdles due to limited accessibilities and poor site conditions. Optimized drilling and blasting parameters can help to achieve this objective. The major challenges of the blast designers lie within deciding blast geometry, namely drill hole diameter, burden, and spacing. The general approaches covered worldwide to determine burden-spacing are based on various rules of thumb, which are based on previous experiences of blasts and the associated outcomes. However, many parameters influencing optimum burden-spacing to achieve desired fragment size are site specific. Sometimes drill geometry is decided based on associated blasting hazards rather than rock fragmentation. The Kuz–Ram model is a worldwide accepted rock fragmentation predictor. The parameters associated with this predictor also include burden-spacing for a blast. Back calculation of burden-spacing from the Kuz–Ram model can be used to achieve desired fragment size. This paper deals with burden-spacing determination by using an empirical approach for the underground stope ring blasting.

Jan 4, 2020

By A. H. Sharbaugh

It is believed that considerable economic benefit would arise if run of mine (ROM) coal from the underground mines in the Winifrede seam could he enriched before shipment to the preparation plant by partial removal of the shale. Shale could comprise up to 50% of the ROM product. Complete mine-mouth separation is not necessary, but any process must be dry and have high Btu recovery. We have conducted a preliminary analysis of coal/shale mixtures from the Winifrede seam and we find that it is quite possible that a 50-50 ROM mixture of coal and shale could be converted to a 60-40 coal-shale mixture by inspection of individual lumps coming from the mine. The device would consist of a feeder/siever section to deliver the ROM coal > 5 cm (2 in) to an inspection station via a conveyor belt. This inspection station decides if a piece is coal or shale, and if it is shale, activates an air jet to blow shale off of the belt. We have evaluated a dielectric loss technique for the inspection device. The potential advantages of the dielectric loss method are high throughput, low capital cost, and no special handling or licenses would be required. Such a single lump inspection technique is made possible because of advances in high speed electronics and servo systems. This paper provides a summary of our analyses on the Winifrede coal sample, a description of a proposed apparatus to separate coal from shale, some of the experiments needed to demonstrate our ideas.

Jan 1, 1984

By John A. Reeves

The unit-train concept of moving raw materials .is considered by many railroad men as the most signifigant contribution to reducing rail freight costs since the introduction of the diesel locomotive. The idea, which involves assigning railroad equipment to only one haul and keeping the equipment rolling results in the maximum utilization of equipment. For example before the unit train was plaged in servige on coal hauled to one of Mid. Continent's customers, about 900 cars and 9 locomotives were needed to move the coal requirements for this plant, compared with. 250 cars and 6 locomotives used by the present scheduling of unit trains. If the economics of unit-train movements are to be achieved, coal companies no longer can use railroad cars as small storage bins on wheels to accumulate their coal in trainload shipments, but, rather, must build large bins which incorporate facilities for the rapid loading of railroad cars in a minimum length of time. In this manner railroad equipment is operated at a high degree of efficiency 'with consequent dollar savings. After negotiations between Mid-Continent, the customers and the Railroad, it was decided a unit train loadout and storage facility at Carbondale was required in order to reduce the delivered price of coal to the customers and thereby contribute to the reduction in the cost of manufacturing steel. Carbondale was selected as the bin site location, because the cost of constructing a railroad to Redstone could not be justified for the tonnages anticipated.

Jan 1, 1969

By G. A. Doyle

The quality of water in mine pit lakes depends in part on the physical limnology, including such factors as thermal and chemical stratification, turnover and the development of anoxic conditions with depth. Limnologic data collected from four existing pit lakes in Montana and Saskatchewan indicate that pit lakes develop a thermocline (temperature stratification) in the upper 10 to 30 m (33 to 100 ft) of the water column. Two o f the pit lakes, 26- and 55-m (85 and 180 ft) deep, undergo seasonal turnover of the entire water column, whereas two deeper, pit lakes, 110 and 240-m (360- to 790 ft) deep, undergo seasonal turnover of only the upper portion of the water column. In the deeper lakes, seasonal mixing does not extend through the entire water column, and a distinct chemocline develops with depth.

Jan 1, 1997

By James E. Lawver

At the present time, the Florida phosphate industry is experiencing one of the worst marked slumps in its one hundred year history. Recent agriculture over-production has caused low grain prices such that the net income of U.S. farmers is expected to drop to its lowest level since the 1932 depression. The farmers' low income, along with high interest rates that preclude them from borrowing to purchase fertilizer, make the immediate U.S. phosphate market outlook bleek at best. The export outlook is also pessimistic due to world recession and the U.S. dollar's high exchange rate. In June, 26% of the phosphate industry's workers were laid off for an indefinite period of time. Despite the immediate painful slump, the long-term outlook for the industry looks good. Florida has enormous reserves and will continue to produce a third of the world's phosphate supply simply by making changes in the present system of mining, beneficiation, waste disposal and land reclamation.

Jan 1, 1983

By Dieter Loh, Mathias Knoll, Florian Werres

When a new tunnelling project starts, it has been a vital tradition for decades to cast and erect master rings horizontally on a flat surface to demonstrate the compliance with dimensional tolerances. Some tenders ask for the erection of two or even three rings upon each other or repeated master ring erections at intervals throughout the project. Especially for large diameters, this is a challenging and risky task for the workforce in the segment factory. A truck-mounted crane is often necessary, and in some cases it can take up to a week to complete a master ring. The concept of virtual rings has the potential to replace this tradition by assembling master rings digitally instead of physically. This is based on a best-fit approach, considering the 3D coordinates from laser tracker measurements of segments or segment moulds. Building a virtual ring, a sub-millimeter accuracy can be achieved, the alignment of neighboring circumferential and ring joints observed, and the fit of bolt holes checked. The traditional method, on the other hand, is discussed controversially despite the significant amount of work and risks—particularly as the horizontal position of the ring and absence of gaskets do not simulate the reality in the excavated tunnel. This paper will highlight the technical aspects of virtual rings, as well as their pros and cons, illustrated by a case study from London Thames Tideway where a total of 30 physical master rings could be replaced by virtual rings.

Jun 13, 2023

By J. D. Miller, J. Hupka

Important aspects of kerosene penetration into tar sand have been investigated. The natural tar sand porosity was measured and used to analyze the performance of the hot water process. Subsequently, pretreatment experiments, using 20-kg tar sand samples (Asphalt Ridge and Whiterocks, Utah) and kerosene as a diluent were carried out at the expected summer temperature (26°C) and the expected winter temperature (-14°C). The natural tar sand porosity accessible by diluent has a crucial impact on the reduction of bitumen viscosity and influences the penetration time required for successful bitumen separation from tar sand by hot water processing. Thus, the tar sand porosity is a critical variable that determines appropriate operating conditions. Experimental results indicate that diluent penetration into the Asphalt Ridge tar sand (high porosity) is almost complete after 30 min, whereas for the Whiterocks tar sand (low porosity) the penetration process is much slower, being still incomplete after 15 hours regardless of the ambient temperature.

Jan 1, 1994

By James Wm. White

Computer-based mine management systems are being used in many surface mines to assign haul trucks, track equipment and manage information. Advances in digital communications allow these systems to be used in underground operations. Underground mine management systems help maximize production by providing gains in equipment and manpower use, drawpoint equalization in block caving operations, preventive maintenance and safety. Current systems use allocated or "locked" train and load-haul-dump (LHD) dispatching. Allocated dispatching rarely optimizes open pit product' on. But it offers an efficient mode of operation underground and where options are more limited. The primary objectives of underground mine management systems are to maximize production and mini¬mize contention time through allocated train, truck or LHD dispatching, traffic control, equipment monitoring and comprehensive reporting. The main components of an underground mine management system include: ? A central computer (personal computer or worksta¬tion) in a central control center. It sends instructions to train, truck or LHD drivers and allows dispatcher interaction. ? A field computer system (FCS). This consists of a touch-screen graphics console (GC) and mobile hub - on each train, truck or LHD to receive and display instructions from the central computer and accept driver input. ? A data radio network based on leaky feeder (data, voice, video) or microcell radios (data only) and advanced token-ring technology. This passes information between the central computer and the FCSs. ? Radio frequency (RF) tags mounted at boxes, weigh bridges, tips and rim tunnel main haulage ways to locate trains or LHDs (Luke, 1993). Such a management system must be in place before implementing computer-based dispatching (Vagenas, 1991) for production optimization.

Jan 1, 1997